Direct Conversion of Methane to C2 and Higher Hydrocarbons

Abstract

Aspects of the invention are associated with the discovery of processes for converting methane (CH 4), present in a methane-containing feed that may be obtained from a variety of sources such as natural gas, to higher hydrocarbons (e.g., C 2 + hydrocarbons) such as C 2 hydrocarbons (e.g., ethane, ethylene, and acetylene) and aromatic hydrocarbons (e.g., benzene, one or more C 1 - or C 2 -substituted benzenes, and/or one or more fused ring aromatic hydrocarbons). Representative processes involve direct, non-oxidative methane conversion (NOMC), such that the need for an oxidant to form CO as an intermediate may advantageously be avoided. This reduces overall complexity and the tendency to promote unwanted side reactions that reduce hydrocarbon yields and lead to CO 2 production.

1 . A process for converting methane in a methane-containing feed to C 2   +  hydrocarbons, the process comprising providing the methane-containing feed to a methane conversion reactor operating under methane conversion conditions to obtain a product comprising the C 2   +  hydrocarbons,
 wherein the methane conversion conditions include an absolute pressure of less than about 1 megapascal (MPa) and a residence time of less than about 60 seconds. 
 
     
     
         2 . The process of  claim 1 , wherein the methane conversion conditions further include a temperature from about 750° C. to about 2000° C. and a hydrogen content in the methane conversion reactor of at least about 10 vol-%. 
     
     
         3 . The process of  claim 1 , wherein the methane-containing feed comprises at least about 20 vol-% of methane. 
     
     
         4 . The process of  claim 1 , wherein the methane-containing feed comprises at least about 90 vol-% of hydrogen and methane in combination. 
     
     
         5 . The process of  claim 1 , wherein the methane-containing feed comprises less than about 5 vol-% of a combined amount of H 2 O, CO 2 , O 2 , and H 2 S. 
     
     
         6 . The process of  claim 1 , wherein the C 2   +  hydrocarbons include one or more C 2  hydrocarbons and one or more aromatic hydrocarbons. 
     
     
         7 . The process of  claim 6 , wherein the one or more C 2  hydrocarbons include ethane, ethylene, and acetylene. 
     
     
         8 . The process of  claim 6 , wherein the one or more aromatic hydrocarbons include benzene, one or more C 1 - or C 2 -substituted benzenes, and one or more fused ring aromatic hydrocarbons. 
     
     
         9 . The process of  claim 1 , wherein a conversion of methane in the methane-containing feed is at least about 15 wt-%. 
     
     
         10 . The process of  claim 1 , wherein methane in the methane-containing feed is converted with a selectivity to the C 2   +  hydrocarbons of at least about 85 wt-%. 
     
     
         11 . The process of  claim 1 , wherein methane in the methane-containing feed is converted with a selectivity to C 2  hydrocarbons of at least about 35 wt-%. 
     
     
         12 . The process of  claim 1 , wherein methane in the methane-containing feed is converted with a selectivity to single ring aromatic hydrocarbons of at least about 45 wt-%. 
     
     
         13 . The process of  claim 1 , wherein methane in the methane-containing feed is converted with a selectivity to coke of less than about 3 wt-%. 
     
     
         14 . The process of  claim 1 , wherein the methane conversion reactor contains a catalyst comprising a methane conversion active metal, or a compound of a methane conversion active metal, wherein the methane conversion active metal is selected from the group consisting of Fe, Cr, Mn, V, Mo, and W. 
     
     
         15 . A process for converting methane in a methane-containing feed to C 2   +  hydrocarbons, the process comprising:
 providing the methane-containing feed to a methane conversion reactor operating under methane conversion conditions to obtain a product comprising (i) the C 2   +  hydrocarbons, including one or more C 2  hydrocarbons and one or more aromatic hydrocarbons, and further comprising (ii) hydrogen and unconverted methane; and 
 separating the product by condensing from the product a liquid, said liquid being enriched in the one or more aromatic hydrocarbons. 
 
     
     
         16 . The process of  claim 15 , wherein the separating provides a vapor, said vapor being enriched in the hydrogen and the unconverted methane. 
     
     
         17 . The process of  claim 16 , wherein the vapor is further enriched in the one or more C 2  hydrocarbons. 
     
     
         18 . The process of  claim 16 , further comprising recycling at least a portion of the vapor to the methane conversion reactor. 
     
     
         19 . A process for converting methane in a methane-containing feed to C 2   +  hydrocarbons and hydrogen, the process comprising providing the methane-containing feed to a methane conversion reactor operating under methane conversion conditions to obtain a product comprising the C 2   +  hydrocarbons,
 the process further comprising, in response to a performance parameter of the process that is below a target value, increasing a hydrogen concentration or hydrogen partial pressure in the methane conversion reactor. 
 
     
     
         20 . The process of  claim 19 , wherein the performance parameter is a conversion of methane in the methane-containing feed or a yield of the C 2   +  hydrocarbons.